To move beyond an energy economy dominated by fossil fuel utilization, high-performance electrochemical cells must be designed for energy storage and conversion. Selective etching is a promising, cost-effective solution-processing method for the large-scale top-down production of nanomaterials for high-performance electrodes. This review outlines general methodologies and mechanisms by which selective etching can be applied to create nanomaterials, including various template-assisted, facet-selective, and electrochemical methods, as well as in-depth case studies of state-of-the-art research involving selectively etched nanomaterials for electrocatalytic and energy storage applications. In addition, the standard design strategies by which the electrochemical performance of selectively etched nanomaterials is enhanced, including increased surface area, morphology, diffusion channels, heterojunction interfaces, and facet reactivity, are discussed. This review provides a foundation of knowledge for researchers seeking the rational design of nanomaterials for electrode application through selective etching.